Myoelectric activity of the cecum and right ventral colon in female ponies

The myoelectric activity of the cecum and right ventral colon (RVC) was studied in 4 female ponies. Eight, bipolar Ag-AgCl electrodes were sequentially placed on the seromuscular layer of the cecum (6 electrodes) and RVC (2 electrodes), and recordings were begun 14 days after surgery. The myoelectric activity for each pony was recorded during 12, 60-minute recording sessions done during the interdigestive period (3 to 7 hours after the morning feeding). Coordinated series of spike bursts were recognized as independent motility patterns in the cecum and in the RVC. Local haustra-haustra myoelectric activity involving approximately 40 cm of the cecal body (0.45 +/- 0.03 spike bursts/min) were detected. A series of spike bursts started at the cecal apex and progressed to, but stopped at, the caudal cecal base (0.40 +/- 0.03 spike bursts/min). Infrequently, a series of spike bursts started at the apex and progressed to the cranial cecal base (0.09 +/- 0.01 spike bursts/min). More commonly, a series of spike bursts with a conduction velocity of 3.8 +/- 0.07 cm/s, began in the cranial base and progressed orally to the cecal apex (0.46 +/- 0.03 spike bursts/min). Spike bursts conducted aborally (propulsion) beginning at the origin of the RVC (0.05 +/- 0.007 spike bursts/min) and spike bursts conducted orally (retropulsion; 0.15 +/- 0.02 spike bursts/min) were seen independent of cecal myoelectric activity. A progressive series of coordinated spike bursts, which began at the cecal apex, were conducted through the cecolic orifice and continued into the RVC (0.42 +/- 0.02 spike bursts/min), representing the only pattern common to the cecum and RVC.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surgical diseases of the equine cecum

Cecal impaction and cecal perforation, the two most common equine cecal diseases, are thought to develop after slowing or interruption of a single progressive motility pattern, which begins in a pacemaker area near the apex, occurs once every 3 minutes, and propels ingesta from the cecum to the right ventral colon. Rectal examination in horses with cecal impaction is the most useful technique to grade the severity of the condition. Medical treatment is undertaken if the impaction is judged to be mild to moderate. Surgical correction of cecal impaction in severe cases requires a ventral midline celiotomy, and exploration reveals a large ingesta-filled cecum and relatively empty large colon. Currently, the techniques of typhlotomy with manual evacuation of ingesta, combined with a complete bypass of the cecum by use of a jejunocolostomy, is the preferred method of surgical management. The use of a cecocolic anastomosis remains a viable alternative surgical procedure. Cecal perforation (CP), a uniformly fatal disease of horses, most often develops when the subtle signs of cecal impaction are missed or are masked by the administration of nonsteroidal antiinflammatory agents. CP can occur in mares around the time of foaling and, in this form, is not associated with cecal outflow dysfunction. Surgical management of cecocecal or cecocolic intussusception is required and involves resection of the diseased portion of cecum, either with extra- or intraluminal techniques. Both the side-to-side and end-to-side jejunocecal anastomoses are useful and successful techniques for bypass of simple or strangulating lesions of the ileum.     

Effects of xylazine and/or butorphanol or neostigmine on myoelectric activity of the cecum and right ventral colon in female ponies

Effects of xylazine HCl (0.5 mg/kg of body weight, IV) and/or butorphanol tartrate (0.04 mg/kg, IV) or neostigmine methylsulfate (0.022 mg/kg, IV) on myoelectric activity of the cecum and right ventral colon were studied in 4 conscious female ponies. Eight bipolar Ag/AgCl electrodes were sequentially placed on the seromuscular layer of the cecum (6 electrodes) and right ventral colon (2 electrodes). Recordings began 30 minutes before and continued for 90 minutes after drug administration. Each drug or drug combination was studied on 2 occasions in each pony. Two major patterns of coordinated spike bursts were identified. A series of coordinated spike bursts began at the cecal base and was conducted to the cecal apex (pattern I). A series of coordinated spike bursts began at the cecal apex, traversed the cecum, cecocolic orifice, and right ventral colon and was termed a progressive pattern (pattern II). Xylazine administration caused a significant decrease in patterns I and II for 20 minutes (P less than 0.05). Butorphanol tartrate administration caused a significant decrease in the progressive pattern for 10 minutes (P less than 0.05) without affecting the orally directed pattern. Administration of the combination of xylazine/butorphanol significantly decreased the frequency of pattern I for 40 minutes (P less than 0.05) and pattern II for 30 minutes (P less than 0.05). Neostigmine administration caused a significant increase in the frequency of pattern II for 30 minutes (P less than 0.05) without affecting pattern I (P greater than 0.05). Changes in conduction velocity of pattern I or II or the duration of spiking activity were not significantly different because of any treatment.     

Cecal amputation within the right ventral colon for surgical treatment of nonreducible cecocolic intussusception in 8 horses

OBJECTIVES: To report a surgical technique for treatment of nonreducible cecocolic intussusception and outcome in 8 horses. STUDY DESIGN: Retrospective study. ANIMALS: Eight horses with nonreducible cecocolic intussusception treated by cecal amputation through a right ventral colotomy. METHODS: Data were obtained from medical records and telephone conversations by using a standardized questionnaire. The large colon was exteriorized and, if necessary, evacuated of its contents through a pelvic flexure enterotomy. A second colotomy was made on the ventral surface of the right ventral colon (RVC) centered over or immediately distal to the intussusceptum. In most horses, attempts to manually reduce the intussusception by pushing the cecum from within the RVC through the cecocolic orifice were unsuccessful. Invaginated cecum was then pulled into the RVC and amputated; the cecum was either ligated with umbilical tape or sutured proximal to the site of amputation. After amputation, the remainder of the invaginated cecum was reduced. After further resection to healthy tissue, the typhlectomy was closed with a double-inverting suture pattern. RESULTS: The median horse age was 2 years (range, 1 to 8 years). Duration of colic ranged from 6 hours to 6 months. Median surgical time was 180 minutes (range, 135 to 300 minutes). Median duration of antibiotic therapy was 7 days (range, 5 to 14 days). Median duration of hospitalization was 12 days (range, 6 to 21 days). All horses survived to hospital discharge. One horse died 3 months postoperatively; however, the remainder survived (median survival, 30 months; range, 6 to 96 months) and returned to or exceeded previous function. CLINICAL RELEVANCE: Despite some contamination during surgery, horses with nonreducible cecocolic intussusception that underwent this method of surgical treatment had a good prognosis.     

Cecal perforation in the horse

The case records of 23 horses with cecal perforation (CP) were reviewed. The horses averaged 4.5 years of age (6 weeks to 13 years) and included 9 intact males, 12 mares, and 2 geldings. Twelve of the horses were Standardbreds, 9 were Thoroughbreds, and 1 each, a Belgian and Morgan. The horses were allotted to 2 groups: group I-13 hospitalized horses in which CP occurred unexpectedly, and group II-10 horses with CP at the time of admission. The horses characteristically had been sick or affected with disease unrelated to the cecum. Sixteen horses had been given nonsteroidal anti-inflammatory drugs before the onset of CP. Twelve of the 13 hospitalized patients (group I) had vague, scarcely recognizable clinical signs of gastrointestinal disease before CP. The clinical signs and clinical laboratory changes that appeared in affected horses were identifiable with severe endotoxin shock, secondary to peritoneal contamination with ingesta and bacteria. All horses died. At necropsy of the horses, the cecum was large and firm and was filled with ingesta, and the colon was empty; however, in 1 postpartum mare, the cecum and colon contained the usual amount of ingesta and were normal in size. In all horses, a single perforation was present, which appeared at various sites. The most common was a transverse perforation along the ventral aspect of the cecal body. Gross and microscopic examinations uncovered no existing disease near the perforation site or in other areas of the cecal wall or cecocolic orifice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cecocolic Anastomosis for the Surgical Management of Cecal Impaction in Horses

Fourteen horses with cecal impaction were treated by cecocolic anastomosis. In nine horses, the anastomosis followed enterotomy and evacuation of the cecal contents, and in two horses it followed saline infusion and massage of the cecum. In three horses, the anastomosis was the only surgical procedure performed. Cecocolic anastomosis was performed between the lateral and dorsal cecal teniae, and the lateral and medial free teniae of the right ventral colon. The anastomosis was hand sutured in five horses. In all other horses, the GIA surgical stapling instrument was used in combination with hand sutured seromuscular layer closures and became the preferred surgical technique. The anastomosis allowed an alternative route for the transit of ingesta from the cecum to the right ventral colon.
Twelve of the 14 horses survived 2 months or longer after surgery (short-term survival rate, 86%) and 10 horses survived 12 months or longer after surgery (long-term survival rate, 71%). Early postoperative complications included mild abdominal pain (6 horses), wound infections (3 horses), fatal peritonitis (2 horses), and large colon distention necessitating reoperation (2 horses).     

Impact of lactic acid fermentation in the large intestine on acute lactic acidosis in cattle

Microbial and fermentation changes in the ingesta of the large intestine and their influence on the pathogenesis of acute lactic acidosis were studied in 4 cows fitted with permanent cannulas in the ileum and cecum. Feed mixture containing 65% of maize was infused into the cecum for several days in amounts of 2 and 4 kg per day. The daily amount was divided in 8 equal portions and given with 3 l of warm physiologic saline solution. During the period of ad libitum feeding of hay, the pH values in cecal digesta were 7.4 to 7.6 and the amount of total volatile fatty acids 40-60 mmol/kg with high molar percentage (87-90 mol%) of acetic acid. As to lactic acid only the L(+) lactic isomer was found in a concentration of about 0.4 mmol/kg. Infusion of low amounts of starch induced mild lactic acid fermentation in the cecum associated with a pronounced increase in the concentration of L(+) and D (-) lactic acid to peak levels of 80 +/- 10 mmol/kg and 7 +/- 1 mmol/kg, respectively. Lactic acid fermentation ceased within 2 to 3 days indicating that the gut microflora had adapted to the starch infusion. Slight decreases of blood pH and bicarbonates in blood as well as a moderate increase of netto acid-base excretion in urine indicated mild changes of acid-base balance, but clinically no pathological symptoms were observed. Higher amounts of infused starch caused pronounced lactic acid production in the large intestine which persisted throughout the experiment. Peak L(+) and D(-) lactic acid concentration in cecal digesta reached on the average 137 +/- 16 mmol/kg and 45 +/- 7 mmol/kg respectively. Significant decreases of blood pH values from 7.41 +/- 0.02 to 7.18 +/- 0.08 (P < 0.001), actual bicarbonate from 28.2 +/- 3.2 to 11.0 +/- 2.6 mmol/l (P < 0.001) and base excess from 3.9 +/- 3.6 to -15.2 +/- 3.8 mmol/l (P < 0.001) were observed. D (-) lactic acid concentration in blood increased to 3.2 +/- 0.4 mmol/l, but L(+) lactic acid values remained unchanged under 1 mmol/l. Clear clinical symptoms of indigestion and intoxication characterized by severe inappetence, ruminal stasis and general weakness were also observed. Typical clinical symptoms of disease as well as blood and urine changes in acid-base balance indicated that lactic acid fermentation in the large intestine contributes considerably to the pathogenesis of acute ruminant lactic acidosis.     

Myoelectric activity of the ileum, cecum, and right ventral colon in ponies during interdigestive, nonfeeding, and digestive periods

Myoelectric activity of the ileum, cecum, and right ventral colon (RVC) was studied in 4 mature ponies. Eight Ag-AgCl bipolar recording electrodes were sutured to the seromuscular layer of the ileum (2 electrodes), cecum (4 electrodes), and RVC (2 electrodes). Myoelectric activity was studied beginning 10 days after surgery. Eight, 60-minute recording sessions were performed in each pony during the interdigestive period, which was the period 3 to 7 hours after the morning feeding. On separate days, food was withheld for 24 hours, and 90-minute recordings were obtained during the nonfeeding period. Ponies were then fed a normal ration, and recordings were continued to obtain data for the digestive (feeding) period. All phases of the migrating myoelectric complex were seen at both ileal electrodes during the interdigestive period, including the periods of no spiking activity (phase 1), irregular spiking activity (phase 2), and regular spiking activity (phase 3). Phase 2 occupied 77% of the total recording time, and the mean duration of phases 1, 2, and 3 was 3.4 +/- 0.2, 12.8 +/- 1.2, and 6.7 +/- 0.7 min, respectively. Frequency of ileal slow waves was 11.8 +/- 0.1/min, and spike burst conduction velocity was 4.7 +/- 0.3 cm/s. A complete migrating myoelectric complex was seen in 11 of 32 tracings (34%) and had a mean duration of 24.2 +/- 2.6 min. The ileal migrating action potential complex, most often seen in phase 2, had a frequency of 4.8 +/- 0.5 spike bursts/h and a conduction velocity of 13.6 +/- 0.4 cm/s.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of cecal bypass via side-to-side ileocolic anastomosis without ileal transection for treatment of cecocolic intussusception in three horses

CASE DESCRIPTION: 3 horses were evaluated for signs of colic; cecocolic intussusception was detected. CLINICAL FINDINGS: Abnormalities detected included diminished intestinal sounds, inflammatory leukogram, dehydration, unremarkable fi ndings via rectal palpation, and ultrasonographic evidence of large intestine intussusception. Laparotomy revealed cecocolic intussusception. TREATMENT AND OUTCOME: Cecal bypass via side-to-side ileocolic anastomosis without ileal transection was performed in each horse by use of an intraluminal anastomosis stapler device. Postoperative complications were minimal, and all horses recovered rapidly and were clinically normal at > 12 months after surgery. CLINICAL RELEVANCE: Cecal bypass via side-to-side ileocolic anastomosis without ileal transection seemed to offer 2 potential advantages over traditional surgical techniques for treating this condition. The risk of abdominal contamination was far less than with techniques in which the colotomy is needed to enable resection of the cecum or techniques in which the ileum is transected. Also, it was technically simpler to perform because there was no need to transect the ileum, oversew the ileal stump, perform cecal resection, or close the mesenteric space created by relocating the jejunal stump to the right ventral colon.     

Obstruction of the cecocolic orifice by ileocecocolic intussusception following jejunocecostomy in a horse

A 4-year-old Thoroughbred stallion was referred for signs of mild to moderate colic, anorexia, and decreased water intake of 3 weeks' duration. Ultrasonographic examination revealed an intussusception, the most common of which would be a cecal inversion or ileocecal intussusception. Surgical exploration identified an ileocecocolic intussusception with extension of the intussusceptum into the right ventral colon; however, the cause of the intussusception could not be identified. The intussusception could not be surgically corrected, and the horse was euthanatized. A side-to-side jejunocecostomy that had been performed previously was identified at necropsy. The ileal stump had intussuscepted into the right ventral colon and become hypertrophied, causing partial obstruction of the cecocolic orifice and clinical signs of colic. In horses requiring an ileocecal or jejunocecal anastomosis, the ileal stump may be left to slough within the cecum as part of the treatment for an irreducible ileocecal intussusception or intentionally inverted into the cecum when the ileal stump is necrotic and cannot be exteriorized and resected. Efforts should be made to minimize the size of the ileal stump to reduce the liklihood of intussusception.     

lleocolostomy A Technique for Surgical Management of Equine Cecal Impaction

Several surgical alternatives have been described for the management of cecal impaction in the horse, but none has met with consistently successful results. This study was done to evaluate a surgical bypass of the cecum by anastomosis of the ileum to the right ventral colon (ileocolostomy). A ventral midline celiotomy was performed on nine adult ponies (155-350 kg) and a mechanically stapled 10 cm side-to-side ileocolostomy was created. In five ponies a complete cecal bypass (CCB) was created by transecting the ileum distal to the anastomosis. In the other four, an incomplete cecal bypass (ICB) was created with no interruption of the ileum. Six horses with clinical cecal impaction also underwent cecal bypass procedures. Five had a CCB and one had an ICB. All the ponies maintained body weight, had no change in consistency of the feces and had no abdominal pain during the 6 month observation period. At necropsy, the lengths of the lateral cecal band, lateral free band of the colon, and the diameter of the anastomotic stoma were compared to measurements made at surgery. The lateral cecal band length decreased significantly more in the CCB ponies than in the ICB ponies (p = 0.008). The anastomotic stoma diameter was significantly larger in the ICB group than in the CCB group (p = 0.032). Five of the six clinical cases recovered and returned to their previous activity. CCB by an ileocolostomy resulted in removal of the cecum from the functional flow of ingesta without complication in the ponies, and was successful in five clinical cases of cecal impaction.     

Equine colonic motility: interactions among wall motion, propulsion, and fluid flow

Transmission of intestinal content with respect to wall position and intraluminal pressure was studied using implanted catheters in portions of the haustrated left ventral colon and nonhaustrated pelvic flexure and left dorsal colon in 3 conscious, standing, and feeding ponies. Wall position and content movement was studied in 1 noncatheterized conscious pony that was standing and eating. When coordinated wall movements involving greater than or equal to 30 cm of adjacent colon were seen, point-to-point content movement accompanied intraluminal pressure peaks occurring in the same direction. Near the pelvic flexure, intraluminal pressure peak maximums coincided and reduced colonic diameters and reduced intercatheter distances. Qualitative observation of 3 related aspects of intestinal motility: wall motion, propulsion, and fluid movement can be studied in the conscious feeding pony.     

Cecal inversion and subsequent colocolic intussusception in a red wolf (Canis rufus gregoryi).

A 2-yr-old female red wolf (Canis rufus gregoryi) presented with weight loss and diarrhea. Abnormal clinical pathology included low serum calcium, sodium, chloride, globulin, and albumin levels. Differential diagnosis included infectious enteritis, intestinal parasitism, inflammatory bowel disease, hepatic or renal disease, and malnutrition. The wolf was treated empirically, but did not improve. A second examination revealed persistent poor musculature and stool quality. Abdominal palpation revealed a firm mass; contrast radiography confirmed an intussusception. Exploratory laparotomy revealed a colocolic intussusception involving the cecum. Following reduction of the colocolic intussusception, cecal inversion (cecocolic intussusception) was identified. Because the cecal inversion could not be reduced, typhlectomy was performed through a colotomy incision. Bacterial culture of peritoneal fluid yielded two strains of Escherichia coli. Postoperatively, the wolf was placed on antibiotics and a soft diet. The diet was gradually returned to its normal formulation and the wolf progressively gained weight. Physical examination 7.5 mo following initial presentation revealed normal body weight and condition. To our knowledge, this is the first recorded incidence of cecal inversion with concurrent colocolic intussusception.     

Changes in motility and ph in the digestive tract of experimentally overfed sheep.

Motility of the digestive tract of 4 sheep was studied with radiotelemetric equipment. After base line records were made, each sheep was overfed with 70 g of grain per kilogram of body weight. The ruminoreticulum did not become static until the ingesta pH was less than 5. The cecum had the same patterns of motility and pH as did the ruminoreticulum, but these returned to normal more quickly in surviving sheep. The motility patterns of the abomasum and the small intestine were more erratic. Results indicated that considerable quantities of grain (substrate for microbial growth) reached the cecum before ruminoreticular motility was inhibited.     

Comparative effects of mu and kappa opiate agonists on the cecocolic motility in the pony.

The electrical and mechanical activity of the large intestine and its response to administration of opiate mu and kappa agonists were assessed from electrodes and inductograph coils chronically implanted on the cecocolic segment in six ponies given a diet of hay and concentrates. Before the drugs were given, migrating complexes propagating from the cecum into the colon occurred at the rate of 1.5 to 16/hour. During this propulsive activity, the cecocolic sphincter opened and closed allowing the outflow of cecal contents and preventing the backflow of colic contents. Each pony was used as its own control and was given fentanyl (0.01 and 0.05 mg/kg of body weight, IV) and U50488H (0.1 and 0.5 mg/kg, IV) at weekly intervals. The mu agonist fentanyl elicited a marked phase of inhibition of the propulsive activity and a closure of the cecocolic sphincter that lasted one to two hours depending on the dose. The kappa agonist U50488H induced an inhibition of the short spiking activity, i.e. of the resting muscle tone. It did not disturb the occurrence of migrating complexes nor that of the openings of the cecocolic sphincter. These kappa compounds may be drugs of choice to alleviate visceral pain in colic stases without inducing delay of transit unlike mu compounds.     

Effects of xylazine butorphanol on cecal arterial blood flow, cecal mechanical activity, and systemic hemodynamics in horses

A chronic model with an ultrasonic transit time blood flow probe and strain gauge force transducers implanted on the cecum was used to evaluate cecal mechanical activity and cecal arterial blood flow in 4 conscious adult horses. Intravenous administration of xylazine (1.1 mg/kg of body weight) significantly decreased heart rate and cardiac output, but significantly increased diastolic pulmonary arterial pressure, mean pulmonary arterial pressure, carotid arterial pressure, and central venous pressure. Lateral cecal arterial blood flow after xylazine administration was decreased substantially more than was cardiac output, suggesting that xylazine caused constriction of the cecal vasculature. This effect of xylazine may have resulted from either a direct effect of xylazine on the cecal vasculature or from reflex vasoconstriction attributable to reduced cardiac output. Intravenous administration of butorphanol tartrate (0.1 mg/kg) did not significantly alter the hemodynamic responses to xylazine. Cecal mechanical activity, as measured by the motility index, was decreased for 120 minutes after administration of xylazine and for 150 minutes after administration of xylazine/butorphanol.     

Cryptosporidiosis in guinea pigs: a retrospective study

Cryptosporidiosis was diagnosed in 81 guinea pigs (Cavia porcellus) from 1979 through 1985 at a research animal diagnostic laboratory. Most of the guinea pigs were juveniles of Hartley stock and originated from 6 commercial laboratory animal suppliers or from one pet store supplier. Common clinical signs reported were failure to gain weight, weight loss, diarrhea, and death. At necropsy, macroscopic findings included emaciation, hyperemia of the small intestine, serosal edema of the cecal wall, and increased fluidity of ingesta throughout the intestines. Oval to round cryptosporidia (1 to 4 microns) were seen microscopically within or on the brush border of mucosal epithelial cells from the duodenum through the cecum. Acute histologic lesions consisted of necrosis and sloughing of enterocytes at the villus tips, inflammation, hyperemia and edema of the lamina propria, and hyperplasia of crypt epithelium. More chronic lesions consisted of marked villus bridging or villus fusion and blunting, metaplasia of the mucosal epithelium, and lymphocytic infiltration of the lamina propria.     

Effects of fenoldopam on cecal blood flow and mechanical activity in horses

Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity in the duodenum, right ventral colon, cecal body, and cecal apex were measured in 6 conscious healthy horses for 60 minutes during and for 120 minutes after IV infusion of 0.9% NaCl solution (control) or fenoldopam. There were no significant changes in these measurements during or after infusion of 0.9% NaCl (saline) solution. Fenoldopam, a selective dopamine-1 receptor agonist, was administered in saline solution at dosages of 0.01, 0.05, and 0.1 micrograms/kg/min. Intravenous infusion of fenoldopam at 0.01 microgram/kg/min significantly increased heart rate, but did not change average carotid arterial pressure or lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at both 0.05 and 0.1 microgram/kg/min significantly increased heart rate, significantly decreased average carotid arterial pressure, and significantly increased lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at 0.01, 0.05, and 0.1 microgram/kg/min did not significantly change the mechanical activity measured by the area under the strain gauge deflection curve for the duodenum, right ventral colon, cecal body, or cecal apex. These results suggest that dopaminergic-1 receptors are present on the colonic vasculature of horses. There was no evidence, however, that dopaminergic-1 receptors exist on the visceral smooth muscle of the duodenum, right ventral colon, cecal body, or cecal apex of horses.     

Strangulating obstruction caused by intestinal herniation through the proximal aspect of the cecocolic fold in 9 horses

OBJECTIVE: To report the clinical and surgical findings and outcome for horses with strangulating obstruction caused by herniation through the proximal aspect of the cecocolic fold. STUDY DESIGN: Retrospective study. ANIMALS: Nine horses. METHODS: Medical records were reviewed for clinical signs, surgical findings and technique, and outcome. Cadaver ponies and necropsy specimens were also used to study the regional anatomy of the cecocolic fold. RESULTS: The ileum and distal jejunum were strangulated in 8 horses, whereas in 1 horse the small intestine and the left ascending colons were incarcerated in a rent in the cecocolic fold. Two horses were euthanatized at surgery, 6 horses had a small intestinal resection (mean length, 3 m; range, 1.5-6.4 m) and an end-to-side jejunocecostomy, and the entrapment was reduced without resection in the horse that had small intestine and ascending colon incarceration; cecocolic fold defects were not closed. One horse was euthanatized 36 hours after surgery because of endotoxemia. Six horses were discharged; 4 were available for long-term follow-up, of which 2 were euthanatized, and 2 were euthanatized 12 and 18 months after surgery because of colic signs. Variations in thickness of the cecocolic fold were observed in specimens obtained from necropsy of other horses and ponies. CONCLUSIONS: Reasons for this defect are unknown, although observed anatomic differences in cecocolic fold thickness may contribute to the development of defects. CLINICAL RELEVANCE: Reduction of the entrapped bowel is easiest when traction is placed on the bowel at a 90 degrees to the base of the cecum. Intestinal incarceration through rents within the proximal part of the cecocolic fold should be considered as a differential diagnosis for strangulating obstruction in horses.     

Visceral analgesia: effects of xylazine, butorphanol, meperidine, and pentazocine in horses

The visceral analgesic, cardiorespiratory, and behavioral effects induced by xylazine, butorphanol, meperidine, and pentazocine were determined in 9 adult horses with colic. Colic was produced by inflating a balloon in the horses' cecum. Heart rate, respiratory rate, mean arterial blood pressure, and cardiac output increased after cecal balloon inflation. Xylazine and butorphanol decreased the hemodynamic response to cecal balloon inflation. Meperidine and pentazocine had minimal effects on the cardiorespiratory changes induced by cecal balloon inflation. Xylazine produced the most pronounced visceral analgesia. The duration of visceral analgesia was longest with xylazine (approx 90 minutes) followed by butorphanol (approx 60 min) and then by meperidine and pentazocine (approx 30 to 35 min). Accurate assessment of the effects of visceral analgesics is dependent upon the use of objective tests to evaluate pain.